System and Method for a Low Noise Amplifier

ABSTRACT

An embodiment described herein includes a low noise amplifier (LNA) including a plurality of separate input terminals, a plurality of transistors, and an output network coupled to a first reference terminal and a single output of the LNA. Each transistor includes a conduction path and a control terminal coupled to one of the plurality of separate input terminals. The output network is also coupled to the conduction path of each of the plurality of transistors.

TECHNICAL FIELD

The present invention relates generally to circuits and amplifiers, and,in particular embodiments, to a system and method for a low noiseamplifier (LNA).

BACKGROUND

Electronic devices used with wireless communication systems, such ascellular phones, GPS receivers, and Wi-Fi enabled notebook and tabletcomputers, generally contain signal processing systems that haveinterfaces to the analog world. Such interfaces may include wire lineand wireless receivers that receive transmitted power and convert thereceived power to an analog or digital signal that may be demodulatedusing analog or digital signal processing techniques. A typical wirelessreceiver architecture includes a low noise amplifier (LNA) thatamplifies the very small signals that may be received by an antenna,provides gain to these small signals and passes an amplified signal tolater amplification and/or signal processing stages. By providing gainat the LNA, subsequent gain processing stages are made insensitive tonoise, thereby enabling a lower system noise figure.

An LNA circuit generally contains at least one transistor and an inputmatching network. The purpose of the input matching network, which maybe made of one or more passive devices such as inductors and capacitors,is to provide an impedance match and/or a noise match to a previousstage, such as an antenna, a filter, an RF switch, or other circuit. LNAimplementations may also include an output matching network, a biasnetwork, and other circuit structures such as a cascode transistor.

As wireless RF devices are being used in more environments with morevaried specifications, the signal path from antenna system to processingcircuit is of increasing importance. Particularly, the placement andusage of LNAs in such varied and demanding systems present variedchallenges. Among other things, challenging aspects of designing modernwireless RF devices may include reducing the effects of attenuation,decreasing sensitivity to noise, reducing cost, reducing design time andchallenge, and increasing system data rates. These challenges, whichoften are conflicting or mutually exclusive, present opportunities forimproved LNA circuits and system configurations.

SUMMARY OF THE INVENTION

In accordance with an embodiment, a low noise amplifier (LNA) includes aplurality of separate input terminals, a plurality of transistors, andan output network coupled to a first reference terminal and a singleoutput of the LNA. Each transistor includes a conduction path and acontrol terminal coupled to one of the plurality of separate inputterminals. The output network is also coupled to the conduction path ofeach of the plurality of transistors.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a block diagram of a conventional system;

FIG. 2 illustrates a block diagram of an embodiment wireless system;

FIG. 3 illustrates a schematic of a conventional low noise amplifier;

FIG. 4 illustrates a block diagram of an embodiment low noise amplifiersystem;

FIGS. 5 a and 5 b illustrate schematics of embodiment low noiseamplifier systems;

FIG. 6 illustrates a schematic of another embodiment low noise amplifiersystem;

FIG. 7 illustrates a schematic of a further embodiment low noiseamplifier system;

FIG. 8 illustrates a more detailed schematic of a low noise amplifiersystem;

FIG. 9 illustrates a more detailed block diagram of another embodimentwireless system;

FIG. 10 illustrates a block diagram of an embodiment method of operatinga wireless system; and

FIG. 11 illustrates a block diagram of an alternative embodimentwireless system.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of various embodiments are discussed in detailbelow. It should be appreciated, however, that the various embodimentsdescribed herein are applicable in a wide variety of specific contexts.The specific embodiments discussed are merely illustrative of specificways to make and use various embodiments, and should not be construed ina limited scope.

Description is made with respect to various embodiments in a specificcontext, namely wireless systems, and more particularly, low noiseamplifiers (LNAs) in antenna systems. Some of the various embodimentsdescribed herein include antenna systems for mobile communications,multiband communications systems, amplifier circuits, LNA circuits, LNAcircuits with matching networks and degeneration elements, and LNAsplaced near antenna systems and distant from processing circuits. Inother embodiments, aspects may also be applied to other applicationsinvolving any type of communication system or amplifier according to anyfashion as known in the art.

According to embodiments described herein, an LNA bank includingmultiple LNAs coupled to a filter bank is disclosed. The filter bank iscoupled to an antenna switch and the antenna switch to an antennasystem. The antenna switch, filter bank, and LNA bank are cascaded inclose proximity to each other in order to reduce attenuation between thecircuits. The LNA bank is coupled to an RF chipset via a single coaxialcable and the RF chipset may be disposed more distant from the LNA bankthan the LNA bank is from the other components. In some embodiments, theLNAs in the LNA bank may only have a single LNA enabled or selected at agiven time. In other embodiments, multiple LNAs in the LNA bank may beenabled of selected simultaneously. In such embodiments, the LNA bankincludes a matching network.

FIG. 1 illustrates a block diagram of a conventional wireless system 100including antenna system 102, diplexer 104, antenna switch 106, filterbank 108, LNA bank 110, and RF chipset 112. According to theconventional art, antenna system 102 receives signals in differentfrequency bands, such as low band (LB), mid band (MB), or high band(HB), and multiplexes the signals at diplexer 104 before conveying thesignals to antenna switch 106 through coaxial cable 114. Antenna switch106 selects a switch coupling to supply a specific filter 1-n in filterbank 108. The specific filter 1-n filters and selects a specificfrequency band and supplies the filtered signals to an LNA 1-n in LNAbank 110. The specific LNA 1-n supplies amplified signals to RF chipset112 where more processing may be performed.

As described in brief in the background, attenuation and noise arerelevant in electronic systems such as wireless system 100. Increasingthe physical distance between each of components 102-112 may increasethe attenuation between each stage, thereby degrading the noiseperformance of the system. Particularly, the coaxial cable 114 coupledbetween antenna system 102 and antenna switch 104 may cause significantattenuation.

Thus, embodiments described herein include a wireless system with anantenna switch, filter bank, and LNA bank placed in close proximity andconfigured to be less affected by attenuation and less sensitive tonoise. Embodiment wireless systems may include an antenna system withmultiple antennas arranged in order to increase signal reception. Theseantennas may be placed more distant from the RF chipset and may becoupled through a coaxial cable. According to various embodiments,amplification is performed in an LNA bank in close proximity to theantenna switch and prior to the coaxial cable in the signal path of thecascaded circuit. Thus, amplification is performed before moresignificant attenuation occurs and the overall noise figure is reduced.

FIG. 2 illustrates a block diagram of an embodiment wireless system 120which illustrates the above mentioned aspects and includes antennasystem 122, antenna switch 124, filter bank 126, LNA bank 128, and RFchipset 132. According to various embodiments, antenna switch 124,filter bank 126, and LNA bank 128 are placed in close proximity onpackage 134 and antenna system 122 may also be placed in close proximityor more distant. In some embodiments, antenna switch 124, filter bank126, and LNA bank 128 placed immediately adjacent to one another. Invarious embodiments, RF chipset 132 is placed further from LNA bank 128and coupled to LNA bank 128 via coaxial cable 130. In specificembodiments, antenna system 122 may include a diplexer and an antennaconfigured to transmit or receive low band (LB) and mid band (MB)signals. In some embodiments, antenna system 122 may include a separatehigh band (HB) antenna or a separate low band (LB) antenna. Antennasystem 122 may also include a combined mid band and high band MB/HBantenna without a diplexer.

According to various embodiments, signals are received at antenna system122. These signals may include multiple frequency bands. For example,the signals may include a low band (LB) of 700-900 MHz, a mid band (MB)of 1.8-2.4 GHz, and a high band (HB) of 2.5-3.5 GHz. Other embodimentsmay include more or fewer bands, as is explained further below, and thebands may range across different frequency ranges. Antenna switch 124 iscontrolled to select specific switch configurations and couple thesignals to specific filters of filters 1-n in filter bank 126. LNA bank128 receives the filtered signals with selected frequency bands from thespecific filters in filter bank 126 at corresponding LNAs of LNAs 1-m inLNA bank 128. Further, the received signals are multiplexed at LNA bank128 and provided on a single output to RF chipset 132 via coaxial cable130.

Depending on the system requirements or usage environment, variousembodiments include numerous variations. For example, antenna system 122may include multiple antennas. In other embodiments, antenna system 122includes a single antenna. Antenna system 122 may include a singletunable antenna or multiple tunable antennas, where each tunable antennais controlled to transmit and receive specific frequency bands. Antennaswitch 124 may include any number of switches. Antenna switch 124 isshown as including two single pole n throw switches, but anyconfiguration is possible. Filter bank 126 includes n filters of anytype, such as passive or active filters for any type of band filtering(low pass, band pass, or high pass). In different embodiments, n mayrange from 1 to any number.

In various embodiments, LNA bank 128 includes m LNAs coupled to filters1-n in filter bank 126 and to coaxial cable 130. The number m of LNAs inLNA bank 128 may be the same as the number n of filters in filter bank126 or may be a different number. An LNA in LNA bank 128 may receiveinputs from a single filter or multiple filters together. The outputs ofLNAs 1-m in LNA bank 128 are multiplexed at the single output andcoupled to coaxial cable 130 in order to be conveyed to RF chipset 132.In various embodiments, multiple LNA banks may be combined and multiplecoaxial connections may be coupled between RF chipset 132 and thevarious LNA banks. In such embodiments, each LNA bank includes multipleLNAs multiplexed at a single output. In some embodiments, only a singleLNA in LNA bank 128 may be enabled or selected at any given time. Inother embodiments, multiple LNAs may be selected or enabled at a giventime and the signals may be multiplexed at the output. Generally,different types of embodiment LNAs are used for multiplexing than forother embodiments, as is described further below in reference to theother figures.

Additional components may be included in wireless system 120 that arenot shown, such as additional communication systems, diplexers,multiplexers, standalone filters, and processing circuits. According tovarious embodiments, wireless system 120 is formed on package 134, whichmay be any type of system. For example, package 134 may be printedcircuit board (PCB) in a mobile device, such as a cell phone or tabletcomputer.

The placement of components including antenna system 122, antenna switch124, filter bank 126, or LNA bank 128 close together includes variousconfigurations in different embodiments. In some embodiments, thecomponents are placed immediately adjacent to one another, or antennasystem 122 may be more distant and antenna switch 124, filter bank 126,and LNA bank 128 are paced immediately adjacent to one another.Specifically, antenna switch 124, filter bank 126, and LNA bank 128 maybe placed less than 1 mm apart on package 134 while RF chipset 132 maybe placed more than 70 mm away from LNA bank 128. Alternatively, theratio of distances may be relevant such that the ratio of the distancesbetween LNA bank 128, filter bank 126, and antenna switch 124 to thedistance between LNA bank 128 and RF chipset 132 is less than 1:2. Inmore particular embodiments, the ratio is less than or equal to 1:10.That is to say, RF chipset 132 is ten times or more further from LNAbank 128 than filter bank 126 is from either LNA bank 128 or antennaswitch 124. In other embodiments, the components including antennaswitch 124, filter bank 126, or LNA bank 128 are placed such that lessthan 10% of the major dimension of wireless system 120 is between twocomponents. For example, wireless system 120 may be a mobile phone witha long side of 5 inches (12.7 cm), the components are placed such thatless than 0.5 inches (1.27 cm) is between two components. In someembodiments, antenna system 122 may also be placed immediately adjacentto antenna switch 124, such as less than 10% of the major dimension ofwireless system 120 or with a ratio less than 1:2 compared to thedistance between LNA bank 128 and RF chipset 132.

Various LNAs will be described in reference to FIGS. 3-8.

FIG. 3 illustrates a schematic of a conventional low noise amplifier(LNA) 140 including amplifying element 142, degeneration element 144,and output tank 146. Amplifying element 142 is connected to an LNA input148 and provides a current path to output tank 146 that provides output150. As shown, amplifying element 142 is a bipolar junction transistor(BJT), output tank includes an inductor and two capacitors, anddegeneration element 144 is an inductor.

FIG. 4 illustrates a block diagram of an embodiment low noise amplifier(LNA) system 160 including amplifiers 162, 164, and 166, degenerationelement 168, matching network 170, and bias circuit 178. According tovarious embodiments, LNA system 160 operates as three LNAs with threeseparate inputs 172, 174, and 176. Each of inputs 172, 174, and 176receives a signal from an antenna or filter as discussed in reference tothe other figures. The signals are amplified by amplifiers 162, 164, and166 and provided as output signals through matching network 170 atoutput 175. Matching network 170 may provide impedance matching onoutput 175; degeneration element 168 may increase the linearity of andadjust the gain of amplifiers 162, 164, or 166; and bias circuit 178selects or enables amplifiers 162, 164, or 166. In some embodiments,matching network 170 may include multiple blocks coupled to amplifiers162, 164, or 166 for impedance matching in specific frequency bands.Likewise, degeneration element 168 may include multiple degenerationelements coupled to amplifiers 162, 164, and 166, such as inductors forexample. In some embodiments, bias circuit 178 may select or enable onlya single amplifier 162, 164, or 166 at a given time. In otherembodiments, bias circuit 178 may select or enable multiple amplifiersat a given time. Specific embodiments are explained in reference toFIGS. 5-8.

FIGS. 5 a and 5 b illustrate schematics of embodiment low noiseamplifier (LNA) systems 180 and 181, each including an output tank, namplifiers, and a degeneration element. According to variousembodiments, LNA system 180 illustrated in FIG. 5 a includes bipolarjunction transistors (BJTs) 1-n controlled at a control terminal byinputs 182 a-182 n, which may be coupled to an antenna system or filterbank as described in reference to the other figures. In LNA system 180,the conduction path of each BJT 1-n is coupled to an individualdegeneration element 184 a-184 n, respectively, that is also coupled toa reference terminal, such as ground. Each degeneration element 184a-184 n may be an inductor, for example, or may include othercomponents. Each BJT 1-n is also coupled to an output tank that iscoupled to a supply terminal, such as VCC, and includes inductor 186 andcapacitors 187 and 188 with output 190 coupled between capacitors 186and 187. In various embodiments, the output tank may be implemented inother types of configurations with any number of inductors, capacitors,or resistors. In some embodiments, the output tank is not an LC tank,but may include another type of output network that is inductive,resistive, capacitive, or some combination thereof. In an embodiment,LNA system 180 may only have one of transistors 1-n selected or enabledat a time, which may be controlled by a biasing circuit coupled to input182 a-182 n, such as bias circuit 178.

According to various embodiments, LNA system 181 illustrated in FIG. 5 bincludes BJTs 1-n coupled to inputs 192 a-192 n, an output tankincluding inductor 196 and capacitors 197 and 198 coupled to output 191,and a single degeneration element 194 that is coupled to the conductionpath of each BJT 1-n. The description of LNA system 180 above alsoapplies to LNA system 181 with the exception that degeneration element194 is a single element coupled to each BJT 1-n.

FIG. 6 illustrates a schematic of another embodiment low noise amplifier(LNA) system 200 including matching networks 202, 204, and 206 coupledthrough amplification elements to input terminals 210 a-210 n and tooutput terminal 208. According to various embodiments, the amplificationelements are BJTs 1-n that include conduction paths from matchingnetworks 202, 204, or 206 through a degeneration element 212 a-212 n toa reference terminal, such as ground, as shown. In various embodiments,the number of transistors 1-n may include any number.

According to various embodiments, each matching network 202, 204, and206 includes a configuration of capacitors and inductors in order toperform impedance matching for a specific frequency band. Matchingnetwork 202 is configured to have a low pass (LP) impedance Zin_LP thatis a low impedance matched to the impedance coupled to output terminal208 for low frequencies. For example, the low band (LB) may includefrequencies ranging from 700 to 900 MHz. Similarly, matching network 204may include inductors and capacitors configured to have a band pass (BP)impedance Zin_BP that is a low impedance matched to the impedancecoupled to output terminal 208 for mid band (MB) frequencies. Forexample, the mid band (MB) may include frequencies ranging from 1.8 to2.4 GHz. Further, matching network 206 may include inductors andcapacitors configured to have a high pass (HP) impedance Zin_HP that isa low impedance matched to the impedance coupled to output terminal 208for high frequencies. For example, the high band (HB) may includefrequencies ranging from 2.5 to 3.5 GHz. In other embodiments, the LB,MB, and HB may include larger or smaller frequency bands. For example,HB may include frequencies ranging above 3.5 GHz.

In the embodiments shown, matching network 202 includes two inductorsand a capacitor configured as a low pass filter; matching network 204includes two inductors and two capacitors configured as a band passfilter; and matching network 206 includes one inductor and twocapacitors configured as a high pass filter. When each matching network202, 204, or 206 is within the respective frequency band LB, MB, or HB,the corresponding impedance Zin_LP, Zin_BP, or Zin_HP is low and matchedto an output line coupled to output terminal 208. In cases where eachmatching network 202, 204, or 206 is outside the respective frequencyband LB, MB, or HB (i.e., out of band), the corresponding impedanceZin_LP, Zin_BP, or Zin_HP is high or near an open circuit. Due to thisconfiguration of LNAs, multiple LNAs coupled to output terminal 208 canbe operating simultaneously and multiple signals may be multiplexed andconveyed on a single coupling connected to output terminal 208, such asa coaxial cable, for example.

In the various embodiments, each matching network 202, 204, or 206 mayinclude multiple inputs and multiple transistors coupled to a singlematching network as shown, for example, with inputs 210 c-210 n coupledto control terminals of transistors 3-n, which include conduction pathsfrom matching network 206 to reference terminals through degenerationelements 212 c-212 n. In such embodiments, the transistors may beimplemented by coupling transistors in parallel. In some embodiments,only a single transistor coupled to each matching network may be enabledor selected at a time. Any configuration as explained, for example, inreference to FIGS. 5 a and 5 b in terms of transistor and degenerationelement coupling may be applied to LNA system 200. Degeneration elements212 a-212 n may include only single inductors as shown. In otherembodiments, degeneration elements 212 a-212 n may include any othercombination of circuit elements.

FIG. 7 illustrates a schematic of further embodiment low noise amplifier(LNA) system 201 including higher order filters in matching networks222, 224, and 226. The description of LNA system 201 is similar to thedescription of LNA system 200 above in reference to FIG. 6. Similarcomponents function in a similar manner.

According to various embodiments, LNA system 201 includes BJTs 1-n withcontrol terminals coupled to inputs 230 a-230 n and conduction pathsfrom matching network 222, 224, or 226 to a reference terminal viadegeneration elements 232 a-232 n. Matching networks 222, 224, and 226include higher order filters than matching networks 202, 204, and 206 inFIG. 6. In various embodiments, matching network 222 includes a low passfilter with three inductors and two capacitors, matching network 224includes a band pass filter with four inductors and four capacitors, andmatching network 226 includes a high pass filter with two inductors andthree capacitors, as illustrated. The higher order of matching networks222, 224, and 226 may allow the frequency bands LB, MB, or HB to be moreclearly defined by increasing the slope of the gain roll-off outside therespective frequency bands. Other embodiments may include any type ofmatching network configuration with any number of circuit components.

FIG. 8 illustrates a more detailed schematic of a low noise amplifier(LNA) system 240 including bias circuit 242, degeneration element 244,output tank 246, and BJT Q1 a with a control terminal coupled to input252. According to various embodiments, output tank 246, which may be animplementation of a matching network as described herein, includesinductor L1 and capacitor C4 coupled to output 250; degeneration element244 includes inductor L2 coupled to a reference such as ground; and biascircuit 242 includes capacitors C1-C3, BJT Q2, and resistors R1-R4. Biascircuit 242 is supplied by a reference current I_(ref) on input 251. Invarious embodiments, additional LNAs are coupled to output 250 in LNAsystem 240 as illustrated by LNA 248, which includes input 253 coupledto bias circuit 243 and BJT Q1 b, as well as degeneration inductor L3.Other configurations of transistors, output tanks, bias circuits, anddegeneration elements are envisioned, as described herein in referenceto the other figures.

LNA system 240 may also include resistor R5. In various embodiments,resistor R5 may allow a different supply voltage to be suppliedinternally in LNA system 240 compared to the supply voltage VCC. LNAsystem 240 may also include capacitors C5 and C6 as well as diodestructures 254, 260, and 262 as well as BJTs 256 and 258 forelectrostatic discharge protection (ESD) and voltage clamping. In aspecific embodiment, each component has a value according to thefollowing ranges: C1: 5-20 pF, C2: 0-10 pF, C3: 0-10 pF, C4: 0-10 pF,C5: 0-15 pF, C6: 0-10 pF, R1: 10-50Ω, R2: 100-500 kΩ, R3: 10-50 kΩ, R4:10-50 kΩ, L1: 0-10 nH, L2: 0-10 nH, and L3: 0-10 nH. In a still morespecific embodiment, each component has a value according to thefollowing: C1=12.8 pF, C2=1.8 pF, C3=2 pF, C4=2.1 pF, C5=7.2 pF, C6=2.79pF, R1=26.66Ω, R2=310 kΩ, R3=20 kΩ, R4=20 kΩ, L1=5.2 nH, L2=1.17 nH, andL3=1.1 nH. Any other values are also envisioned for each component.

Generally, in all the figures presented herein, the amplifying elementsand/or transistors may be implemented as any type of transistor. Forexample, transistors described herein may include complementary metaloxide semiconductor (CMOS) transistors, BJTs, gallium arsenidetransistors, FinFETs, or any other implementation as is known in theart.

FIG. 9 illustrates a more detailed block diagram of another embodimentwireless system 300 including antenna switch 306, filters B1-B10, LNAbank 308, LNA bank 310, and select switch 318. According to variousembodiments, inputs are received from an antenna or group of antennas atinput 302. The signals received at input 302 are conveyed to antennaswitch 306. Antenna switch 306 selects filters B1-B10, which includefrequency bands B1-B10. Selected signals from antenna switch 306 aresupplied to filters B1-B10 that filter the signals and supply bandsB1-B10 to LNAs 1-8 in LNA bank 308 and LNA bank 310 via inductorsL11-L18. Outputs of LNA banks 308 and 310 are coupled to select switch318 that selects one of the signal paths to provide as output RFOUT.

According to various embodiments, LNA banks 308 and 310 include areduced number of outputs by including LNAs with outputs coupledtogether and diplexed or multiplexed, as described in reference to theother figures included herein. For example, LNA 1 and LNA 3 havediplexed outputs coupled to terminal RX4 on switch 318, LNA 2 and LNA 3have diplexed outputs coupled to terminal RX3 on switch 318, LNA 5 andLNA 7 have diplexed outputs coupled to terminal RX2 on switch 318, andLNA 6 and LNA 8 have diplexed outputs coupled to terminal RX1 on switch318. Outputs of each LNA may also be multiplexed or diplexed usingadditional components such as a low pass filter or band pass filter. Insome embodiments, an LNA bank only has a single common output coupled tothe outputs of every LNA in the LNA bank (not shown), as describedherein in reference to the other figures.

In various embodiments, band filters B1-B10 may include any frequencyband such as low band, mid band, and high band frequencies. In someembodiments, band filters may include frequency bands with frequenciesranging from 100 MHz to 10 GHz with bands as narrow as a 0.01 MHz or aswide as 200 MHz. Other frequency bands may be included in alternativeembodiments. In one embodiment, LNA bank 308 is coupled to low bandsignals and LNA bank 310 is coupled to high band signals.

In some embodiments, wireless system 300 is disposed on a single circuitboard 320. The circuit board 320 may be part of a mobile phone or othermobile device. In an embodiment, blocks 308 and 310 are each formed on aseparate semiconductor die or circuit board before being packaged inwireless system 300.

FIG. 10 illustrates a block diagram of an embodiment method of operatinga wireless system 400, including steps 402-410, in order to convey aplurality of signals in a plurality of frequency bands. According tovarious embodiments, step 402 includes receiving a first signal at aninput of a first LNA and step 404 includes receiving a second signal atan input of a second LNA. In step 406, the first signal is amplified atthe first LNA and the second signal is amplified at the second LNA. Thefirst and second signals are multiplexed at a shared output of the firstand second LNAs in step 408. Step 410 includes supplying the first andsecond signals to a processing circuit on a single coupling line coupledto the shared output. In various embodiments, method of operation 400may include additional steps and steps 402-410 may be performed invarious different orders.

FIG. 11 illustrates a block diagram of an alternative embodimentwireless system 340 including antenna system 342, antenna switch 344,filter bank 346, LNA bank 348 including LNAs 1-n, and RF chipset 350. Insuch alternative embodiments, each LNA 1-n includes a separate couplingto RF chipset 350. Wireless system 340 may be included on circuit board352.

According to various embodiments, a low noise amplifier (LNA) includes aplurality of separate input terminals, a plurality of transistors, andan output network coupled to a first reference terminal and a singleoutput of the LNA. Each transistor includes a conduction path and acontrol terminal coupled to one of the plurality of separate inputterminals. The output network is also coupled to the conduction path ofeach of the plurality of transistors.

In various embodiments, the LNA includes a plurality of degenerationelements and each degeneration element is coupled between the conductionpath of a transistor of the plurality of transistors and a secondreference terminal. The LNA may also include a degeneration elementcoupled between the conduction path of each transistor of the pluralityof transistors and a second reference terminal. In some embodiments, thedegeneration element is an inductor.

In various embodiments, the output network includes an LC tank. In someembodiments, the output network includes a complex impedancesubstantially matched to an impedance coupled to the single output ofthe LNA. The output network may have a first impedance in-band and asecond impedance out of band. The second impedance is greater than thefirst impedance. In one embodiment, the first impedance is substantiallymatched to an impedance coupled to the single output of the LNA. Invarious embodiments, the LNA also includes a bias network coupled to thecontrol terminal of each of the plurality of transistors. The biasnetwork is configured to activate one transistor of the plurality oftransistors at a time.

According to various embodiments, a low noise amplifier (LNA) bankincludes a first LNA and a second LNA. The first LNA includes a firsttransistor including a control terminal coupled to a first input of theLNA bank and a first output network coupled to a conduction path of thefirst transistor and an output of the LNA bank. The first output networkis configured to have a first type of output impedance in a firstfrequency band and a second type of output impedance outside the firstfrequency band. The second LNA includes a second transistor including acontrol terminal coupled to a second input of the LNA bank and a secondoutput network coupled to a conduction path of the second transistor andthe output of the LNA bank. The second output network is configured tohave the first type of output impedance in a second frequency band andthe second type of output impedance outside the second frequency band.

In various embodiments, the first output network includes a first LCtank and the second output network includes a second LC tank. The LNAbank may also include a third LNA including a third transistor includinga control terminal coupled to a third input of the LNA bank and a thirdoutput network coupled to a conduction path of the third transistor andthe output of the LNA bank. The third output network is configured tohave the first type of output impedance in a third frequency band andthe second type of output impedance outside the third frequency band. Insome embodiments, the first frequency band is a low band, the secondfrequency band is a mid band, and the third frequency band is a highband. The LNA bank may also include a first degeneration element coupledto the conduction path of the first transistor, a second degenerationelement coupled to the conduction path of the second transistor, and athird degeneration element coupled to the conduction path of the thirdtransistor. The first, second, and third degeneration elements may eachinclude an inductor.

In various embodiments, the first or second transistors include aplurality of transistors, each transistor including control terminalscoupled to a plurality of separate inputs of the LNA bank and conductionpaths coupled to the respective first or second output networks. In someembodiments, the first type of output impedance is substantially matchedto an impedance coupled to the output of the LNA bank in respectivefrequency bands and the second type of output impedance is higher thanthe first type of output impedance in respective frequency bands. Inparticular embodiments, the first type of output impedance is 50 S2 inrespective frequency bands and the second type of output impedance ishigher than 200 S2 in respective frequency bands.

According to various embodiments, a method includes receiving a firstsignal at an input of a first low noise amplifier (LNA), receiving asecond signal at an input of a second LNA, amplifying the first signalat the first LNA and amplifying the second signal at the second LNA,multiplexing the first and second signals at a shared output line of thefirst LNA and the second LNA, and supplying the first and second signalsto a processing circuit on a single coupling line coupled to the sharedoutput.

In various embodiments, the first LNA, the second LNA, and the sharedoutput line are formed on a single semiconductor die. Receiving thefirst signal and receiving the second signal may be performedsimultaneously and the first and second signals may be supplied to theprocessing circuit simultaneously. In some embodiments, receiving thefirst and second signals includes receiving first and second signalsfrom a filter bank that is coupled to an antenna circuit. The filterbank, the first LNA, and the second LNA may be disposed in proximity toone another on a same chip in proportion to a size of the chip. In somespecific embodiments, disposed in proximity includes disposedimmediately adjacent on a same chip. In other embodiments, disposed inproximity includes disposed within 10% of a longest dimension of thechip. Further, the single coupling line may be a coaxial cable and theprocessing circuit may be disposed on the same chip distant from theantenna circuit, the filter bank, the first LNA, and the second LNA.

According to various embodiments, a wireless system includes an antennasystem, a filter bank coupled to the antenna system, and a low noiseamplifier (LNA) bank coupled to the filter bank. The filter bankincludes a plurality of filters and each filter in the plurality offilters is coupled to the antenna system. The LNA bank includes aplurality of LNAs coupled to the plurality of filters and to a singleoutput of the LNA bank. The single output of the LNA bank is configuredto be coupled to a processing circuit located electrically distant theLNA bank. The antenna system is located within a first distance from thefilter bank, the LNA bank is located within the first distance from thefilter bank, and the LNA bank is configured to be located within asecond distance from the processing circuit.

In various embodiments, the second distance is greater than or equal to5 times the first distance. The wireless system may also include anantenna switch coupled between the antenna system and the filter bank.The antenna switch includes a plurality of switch outputs and eachswitch output of the plurality of switch outputs is coupled to a filterin the plurality of filters. In some embodiments, the wireless systemincludes a mobile communication device disposed on a single circuitboard. In such an embodiment, the antenna switch is disposed immediatelyadjacent to the filter bank and the filter bank is disposed immediatelyadjacent to the LNA bank. Some embodiments include the processingcircuit. The single output of the LNA bank may be coupled to theprocessing circuit through a coaxial cable.

In various embodiments, the LNA bank also includes a biasing circuitcoupled between the plurality of filters and the plurality of LNAs. Thebiasing circuit is configured to enable a single LNA of the plurality ofLNAs at a time. The LNA bank may also include a matching network coupledbetween the plurality of LNAs and the single output of the LNA bank. Thematching network includes a plurality of LC tanks coupled to theplurality of LNAs and each LC tank of the plurality of LC tanks isconfigured to match an output impedance seen on the single output of theLNA bank in a specific frequency band.

According to various embodiments, a wireless system includes an antennasystem, a low noise amplifier (LNA) bank coupled to the antenna system,and a processing circuit coupled to the single output of the LNA bankvia a coaxial cable. The LNA bank includes a plurality of LNAs coupledto a single output of the LNA bank and formed on a single semiconductordie. The LNA bank is located within a first distance of the antennasystem and the processing circuit is located outside a second distancethat is at least 10 times greater than the first distance. In variousembodiments, the first distance is 1 mm and the second distance is 70mm.

According to embodiments of the invention, advantages may include lowattenuation between signal sources and processing circuits due toimproved LNA placement near the signal source. Other advantages mayinclude reduced routing effort for printed circuit board (PCB) layoutand design due to diplexing and multiplexing of outputs for LNAs. Insome embodiments, a smaller PCB may be used due to the reduced routingeffort. Further advantages include a reduced noise figure and highersensitivity in some embodiments.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

1-9. (canceled)
 10. An amplifier system including a low noise amplifier(LNA) bank comprising: a first LNA comprising: a first transistorincluding a control terminal coupled to a first input of the LNA bank,and a first output network coupled to a conduction path of the firsttransistor and an output of the LNA bank, wherein the first outputnetwork is configured to have a first type of output impedance in afirst frequency band and a second type of output impedance outside thefirst frequency band; and a second LNA comprising: a second transistorincluding a control terminal coupled to a second input of the LNA bank,and a second output network coupled to a conduction path of the secondtransistor and the output of the LNA bank, wherein the second outputnetwork is configured to have the first type of output impedance in asecond frequency band and the second type of output impedance outsidethe second frequency band.
 11. The amplifier system of claim 10, whereinthe first output network comprises a first LC tank and the second outputnetwork comprises a second LC tank.
 12. The amplifier system of claim10, further comprising a third LNA comprising: a third transistorincluding a control terminal coupled to a third input of the LNA bank,and a third output network coupled to a conduction path of the thirdtransistor and the output of the LNA bank, wherein the third outputnetwork is configured to have the first type of output impedance in athird frequency band and the second type of output impedance outside thethird frequency band.
 13. The amplifier system of claim 12, wherein: thefirst frequency band is a low band; the second frequency band is a midband; and the third frequency band is a high band.
 14. The amplifiersystem of claim 12, further comprising: a first degeneration elementcoupled to the conduction path of the first transistor; a seconddegeneration element coupled to the conduction path of the secondtransistor; and a third degeneration element coupled to the conductionpath of the third transistor.
 15. The amplifier system of claim 14,wherein the first, second, and third degeneration elements each comprisean inductor.
 16. The amplifier system of claim 10, wherein the first orsecond transistors comprise a plurality of transistors comprising:control terminals coupled to a plurality of separate inputs of the LNAbank, and conduction paths coupled to the respective first or secondoutput networks.
 17. The amplifier system of claim 10, wherein: thefirst type of output impedance is substantially matched to an impedancecoupled to the output of the LNA bank in respective frequency bands, andthe second type of output impedance is higher than the first type ofoutput impedance in respective frequency bands.
 18. The amplifier systemof claim 10, wherein: the first type of output impedance is 50Ω inrespective frequency bands, and the second type of output impedance ishigher than 200Ω in respective frequency bands. 19-25. (canceled) 26.The amplifier system of claim 10, further comprising: an antenna system;a filter bank coupled to the antenna system, wherein the filter bankcomprises a plurality of filters and each filter in the plurality offilters is coupled to the antenna system; and wherein the first LNA iscoupled to a first filter in the plurality of filters and the second LNAis coupled to a second filter in the plurality of filters, the output ofthe LNA bank is configured to be coupled to a processing circuit, andthe antenna system is located within a first distance from the filterbank, the LNA bank is located within the first distance from the filterbank, and the LNA bank is configured to be located within a seconddistance from the processing circuit.
 27. The amplifier system of claim26, wherein the second distance is greater than or equal to 5 times thefirst distance.
 28. The amplifier system of claim 26, further comprisingan antenna switch coupled between the antenna system and the filterbank, wherein the antenna switch comprises a plurality of switch outputsand each switch output of the plurality of switch outputs is coupled toa filter in the plurality of filters.
 29. The amplifier system of claim28, wherein the amplifier system comprises a mobile communication devicedisposed on a single circuit board, and wherein the antenna switch isdisposed immediately adjacent to the filter bank and the filter bank isdisposed immediately adjacent to the LNA bank.
 30. The amplifier systemof claim 26, further comprising the processing circuit.
 31. Theamplifier system of claim 30, wherein the output of the LNA bank iscoupled to the processing circuit through a coaxial cable.
 32. Theamplifier system of claim 26, wherein the LNA bank further comprises abiasing circuit coupled between the plurality of filters and the firstLNA and the second LNA, and wherein the biasing circuit is configured toenable a single LNA of the LNA bank at a time. 33-34. (canceled)
 35. Anamplifier system of claim 10, further comprising: an antenna system; anda processing circuit coupled to the output of the LNA bank via a coaxialcable, wherein the LNA bank is located within a first distance of theantenna system and the processing circuit is located outside a seconddistance that is at least 10 times greater than the first distance. 36.The amplifier system of claim 35, wherein the first distance is 1 mm andthe second distance is 70 mm.
 37. A method of operating an amplifiersystem including a low noise amplifier (LNA) bank, the methodcomprising: receiving a first signal at a first input of the LNA bank,the first input of the LNA bank coupled to a first LNA in the LNA bank,the first LNA comprising: a first transistor including a controlterminal coupled to the first input of the LNA bank, and a first outputnetwork coupled to a conduction path of the first transistor and anoutput of the LNA bank, wherein the first output network is configuredto have a first type of output impedance in a first frequency band and asecond type of output impedance outside the first frequency band;receiving a second signal at a second input of the LNA bank, the secondinput of the LNA bank coupled to a second LNA, the second LNAcomprising: a second transistor including a control terminal coupled tothe second input of the LNA bank, and a second output network coupled toa conduction path of the second transistor and the output of the LNAbank, wherein the second output network is configured to have the firsttype of output impedance in a second frequency band and the second typeof output impedance outside the second frequency band; amplifying thefirst signal at the first LNA and amplifying the second signal at thesecond LNA; multiplexing the first signal and the second signal at theoutput of the LNA bank; and supplying the first signal and the secondsignal to a processing circuit on a single coupling line coupled to theoutput of the LNA bank.
 38. The method of claim 37, wherein the firstLNA, the second LNA, and the output of the LNA bank are formed on asingle semiconductor die.
 39. The method of claim 37, wherein receivingthe first signal and receiving the second signal are performedsimultaneously and the first signal and the second signals are suppliedto the processing circuit simultaneously.
 40. The method of claim 37,wherein receiving the first and second signals comprises receiving firstand second signals from a filter bank, the filter bank coupled to anantenna circuit, and wherein the filter bank, the first LNA, and thesecond LNA are disposed in proximity to one another on a first chip inproportion to a size of the first chip.
 41. The method of claim 40,wherein disposed in proximity comprises disposed immediately adjacent ona same chip.
 42. The method of claim 40, wherein disposed in proximitycomprises disposed within 10% of a longest dimension of the first chip.43. The method of claim 40, wherein the single coupling line comprises acoaxial cable and the processing circuit is disposed on the first chipdistant from the antenna circuit, the filter bank, the first LNA, andthe second LNA.